Commit 9380cf5a authored Sep 09, 2015 by Heiko Carstens Committed by Martin Schwidefsky Sep 17, 2015

s390: fix floating point register corruption



The critical section cleanup code misses to add the offset of the
thread_struct to the task address.
Therefore, if the critical section code gets executed, it may corrupt
the task struct or restore the contents of the floating point registers
from the wrong memory location.
Fixes d0164ee2 "s390/kernel: remove save_fpu_regs() parameter and use
__LC_CURRENT instead".

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

parent 88d64253

arch/s390/kernel/entry.S

+2 −0

Original line number	Diff line number	Diff line
		@@ -1191,6 +1191,7 @@ cleanup_critical:
		clg %r9,BASED(.Lcleanup_save_fpu_fpc_end)
		jhe 1f
		lg %r2,__LC_CURRENT
		aghi %r2,__TASK_thread
		0: # Store floating-point controls
		stfpc __THREAD_FPU_fpc(%r2)
		1: # Load register save area and check if VX is active
		@@ -1252,6 +1253,7 @@ cleanup_critical:
		clg %r9,BASED(.Lcleanup_load_fpu_regs_vx_ctl)
		jhe 6f
		lg %r4,__LC_CURRENT
		aghi %r4,__TASK_thread
		lfpc __THREAD_FPU_fpc(%r4)
		tm __THREAD_FPU_flags+3(%r4),FPU_USE_VX # VX-enabled task ?
		lg %r4,__THREAD_FPU_regs(%r4) # %r4 <- reg save area